Vaisala INTERCAP HMDW80 SERIES Especificaciones descargar pdf (Pagina 13)

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Humidity sensors from Vaisala.

The Right Humidity Instrument for the Job

No matter what the application, the

total range of gas temperatures and

expected water vapor levels must be

known in order to decide the optimal

humidity parameters and the optimal

instrument for the environment.

The process pressure must also be

known when measuring humidity

within the process. In addition, it

must be decided whether to make the

measurement at the process pressure

or at some other pressure. For gases

other than air, the gas composition

must be known.

The terms probe, transmitter, and

sensor describe products that

measure humidity. The probe is the

part of the product that contains

the humidity sensor. The probe may

be rigidly bound to the transmitter

or connected with a flexible cable.

The transmitter provides the output

signal.

Vaisala designs and manufactures

a range of products for measuring

relative humidity, temperature,

and dew point based on HUMICAP

®

and DRYCAP

®

sensors. All Vaisala

humidity instruments feature

built-in temperature compensation

to minimize the errors caused by

temperature variations and operation

at extremes of temperature. Many

of the products include built-in

calculations for other humidity

parameters.

Protect the Sensor

and Electronics with

the Right Filter

As well as screening the sensor from

any stray electromagnetic fields,

the filter protects the sensor from

dust, dirt, and mechanical stress.

A membrane or netting filter is a

good alternative for the majority of

applications. In temperatures above

80°C, in high pressure, or in rapidly

moving air up to 75 m/sec, a sintered

filter should be used.

A suitable protective enclosure

protects the instrument electronics

Protective filters for Vaisala’s humidity

instruments.

manufacture and the measurement

on site – introduces measurement

error. The sum of these potential

errors is the uncertainty of the

measurement.

When selecting a humidity sensor,

consider the following factors

associated with accuracy:

• Linearityovertheworkingrange

• Hysteresisandrepeatability

• Stabilityoveraperiodoftime

• Temperaturedependenceofthe

sensor

During manufacture, Vaisala

products are compared and adjusted

against factory standards that are

from dust, dirt, and excessive

humidity. An enclosure with an IP65

or NEMA 4 classification gives good

protection against dust and sprayed

water. The cable entry points need to

be sealed during installation.

When using the instrument outside,

it should be mounted in a radiation

shield or Stevenson screen to prevent

solar radiation or extremes of weather

from affecting the measurement.

Must the Instrument

Tolerate Condensation?

Making good quality humidity

measurements in near-condensing

conditions is very challenging.

Warmed probe technology ensures

reliable measurements when

measuring relative humidity close

to saturation point. The humidity

level of the warmed probe always

stays below the ambient level, where

condensation occurs.

Must the Instrument

Withstand Exposure to

Chemicals?

A chemical purge feature helps to

maintain measurement accuracy

in environments with a high

concentration of chemicals or

directly traceable to internationally

recognized standards. The

calibration chain is detailed in the

certificates that are supplied with the

majority of Vaisala products.

Humidity

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